Pressure regulators for use in medical devices such as a gas delivery system often require high accuracy of the regulated output pressure. In recent years there has been a move towards miniaturisation and weight reduction of medical devices including devices using pressure regulators to allow for increased convenience and portability. Accordingly there have been attempts to produce miniature pressure regulators to satisfy these size and weight requirements including single stage regulators for use with supply pressures of typically 4-10 bar, producing a reduced regulated output pressure. Such single stage miniature pressure regulators may also have applicability in scientific equipment and high precision industrial machinery.
“Pressure droop” is a characteristic seen in known regulators whereby the pressure at the regulator outlet falls, deviating away from the set point pressure as the flow rate through the regulator is increased.
In seeking to reduce the size of pressure regulators the size often has to be compromised to achieve the required regulator performance particularly for increased flow capacity and the reduction of outlet “pressure droop”—typically by increasing the size of regulator to achieve the performance requirement. Another problem in known pressure regulators is: if a significant leak path occurs in the regulator diaphragm, the outlet fluid pressure is likely to increase to a level well above the set outlet pressure. The present invention seeks to provide a solution to one or more of these problems.